1. Field of the Invention
This invention relates to the stabilization of chlorofluorocarbon/polyester polyol premixes, and the use of such premixes for the preparation of polyurethane and polyisocyanurate foams.
2. Description of the Prior Art
The use of foamed polyurethanes and polyisocyanurates as thermal insulating materials, packaging foams, etc. is widespread. It is common practice in the manufacture of such cellular foam materials to mix two preformulated components, commonly called the A-component and the B-component. Typically, the A-component contains the isocyanate compound that must be reacted with the constituents of the B-component premix to form the foam, and this B-component premix commonly contains the balance of the foam ingredients, namely, polyol, blowing agent, which is normally a chlorofluorocarbon (e.g., CCl.sub.3 F, CFC-11), surfactant and catalyst.
An inexpensive source of polyols for foam insulation systems is now available through the use of waste stream aromatic polyesters and aromatic polyesters reclaimed from bottles, film scrap, etc. Unfortunately, premixes containing these polyester polyols are unstable with regard to reactivity at room or elevated temperature when such premixes also contain an amine catalyst. Apparently, acid formed as a product of CFC-11/polyol reactions affects the efficiency of the amine catalyst. The result is a loss of reactivity of the premix. Furthermore, when the stored polyol premixes are employed in the preparation of polyurethane and polyisocyanurate cellular materials, there may result a degradation in foam cell structure and color.
Therefore, there is a need for simple and inexpensive ways of providing storage-stable premixes containing polyester polyols for the preparation of polyurethane and polyisocyanurate foam articles.